Paper cassette and image forming apparatus including the same

ABSTRACT

A paper cassette and an image forming apparatus including the paper cassette are provided. The paper cassette includes a cassette frame having a bottom plate on which sheets of paper are loaded. A first member restricts the paper loaded on the bottom plate from moving in a width direction of the paper. A second member restricts the paper from moving in a length direction. A connecting member connects the first member and the second member and is mounted on the bottom plate to be linearly reciprocated.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 10-2004-0084370, filed on Oct. 21, 2004, in the Korean Intellectual Property Office, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus. More particularly, the present invention relates to a paper cassette for loading sheets of paper on which images are printed and an image forming apparatus including the paper cassette.

2. Description of the Related Art

Generally, an image forming apparatus is an apparatus for printing predetermined images on paper, such as a printer or a copying machine, and includes a printing unit for printing the images and a paper cassette for loading the paper supplied to the printing unit.

FIG. 1 is an exploded perspective view of a conventional paper cassette. The conventional paper cassette includes a cassette frame 1 having a space where the paper is loaded. A first member 11 and a second member 13 confine the paper in a width direction and a length direction so that the paper loaded on a lower plate 2 of the cassette frame 1 cannot move from that position.

The lower plate 2 includes a plurality of insertion recesses 5 and 6 in the width direction of the paper, and a plurality of insertion recesses 7 and 8 in the length direction of the paper, according to a size of the paper that is generally used. The first member 11 is inserted into one of the insertion recesses 5 and 6 and the second member 13 is inserted into one of the insertion recesses 7 and 8 to support the paper so that the paper does not escape from the position, according to the size of the loaded paper.

However, according to the conventional paper cassette, the first member 11 and the second member 13 should be reset whenever the size of the paper is changed.

Alternatively, although it is not shown in the drawings, a paper cassette can have the first member and the second member be slidable in the width and length directions of the paper to be set on the lower plate of the cassette frame. However, in the above paper cassettes, the first member and the second member should be reset whenever the size of paper is changed, and a jam may be generated during picking up and conveying the loaded paper due to unskilled setting of a user.

Accordingly, a need exists for an image forming apparatus having an improved paper cassette to substantially eliminate paper jams when changing the paper size.

SUMMARY OF THE INVENTION

The present invention provides a paper cassette including a first member that restricts paper from being moved in a width direction of the paper and a second member that restricts paper from being moved in a length direction of the paper that may be slid in connection with each other.

According to an aspect of the present invention, a paper cassette includes a cassette frame having a bottom plate on which sheets of paper are loaded. A first member restricts the paper loaded on the bottom plate from moving in a width direction of the paper. A second member restricts the paper from moving in a length direction. A connecting member connects the first member and the second member and is mounted on the bottom plate to be linearly reciprocated.

A guide recess extends linearly in the bottom plate. The connecting member may be mounted on the bottom plate to be linearly reciprocated along the guide recess.

The guide recess may be extended along a virtual line that is slanted in a clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.

The guide recess may be extended along a virtual line that is slanted in a counter-clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.

The connecting member may include a rack portion where a gear is formed. The bottom plate includes a pinion gear that is engaged with the rack portion, thus the connecting member is linearly moved by the rotation of the pinion gear.

The paper cassette may further include a position fixation unit fixing positions of the first member, the second member, and the connecting member according to the size of paper.

The paper cassette may further include a size recognition unit recognizing the size of paper that may be loaded on the bottom plate in a state where the first and second members are set.

A slant surface guiding the paper to an appropriate loading position when the paper is loaded and a stepped surface restricting the loaded paper from escaping that position may be formed on upper end portions of the first and second members.

According to another aspect of the present invention, an image forming apparatus includes a printing unit printing images. A paper cassette loads sheets of paper that are supplied to the printing unit. The paper cassette includes a cassette frame having a bottom plate on which sheets of paper are loaded. A first member restricts the paper loaded on the bottom plate from moving in a width direction of the paper. A second member restricts the paper from moving in a length direction. A connecting member connects the first member and the second member and is mounted on the bottom plate to be linearly reciprocated.

A guide recess extends linearly in the bottom plate. The connecting member may be mounted on the bottom plate to be linearly reciprocated along the guide recess.

The guide recess may be extended along a virtual line that is slanted in a clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.

The guide recess may be extended along a virtual line that is slanted in a counter-clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.

The connecting member may include a rack portion in which a gear is formed. The bottom plate includes a pinion gear that is engaged with the rack portion, thus the connecting member is linearly moved by the rotation of the pinion gear.

The paper cassette may further include a position fixation unit fixing positions of the first member, the second member, and the connecting member according to the size of paper.

The paper cassette may further include a size recognition unit recognizing the size of paper that may be loaded on the bottom plate in a state where the first and second members are set.

A slant surface guiding the paper to an appropriate loading position when the paper is loaded and a stepped surface restricting the loaded paper from escaping that position may be formed on upper end portions of the first and second members.

Other objects, advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:

FIG. 1 is an exploded perspective view of a conventional paper cassette;

FIG. 2 is a schematic cross-sectional view of an image forming apparatus according to an exemplary embodiment of the present invention;

FIG. 3 is an exploded perspective view of a paper cassette according to an exemplary embodiment of the present invention;

FIG. 4 is a top plan view of the paper cassette in FIG. 3 according to an exemplary embodiment of the present invention;

FIG. 5 is a cross-sectional view of the paper cassette along line V-V direction of FIG. 4;

FIG. 6 is a top plan view of a paper cassette according to another exemplary embodiment of the present invention; and

FIG. 7 is a top plan view of a paper cassette according to still another exemplary embodiment of the present invention.

Throughout the drawings, like reference numerals will be understood to refer to like parts, components and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 2 is a schematic cross-sectional view of an image forming apparatus according to an exemplary embodiment of the present invention. FIG. 3 is an exploded perspective view of a paper cassette according to an exemplary embodiment of the present invention. FIG. 4 is a top plan view of the paper cassette of FIG. 3. FIG. 5 is a cross-sectional view of the paper cassette cut along line V-V of FIG. 4.

Referring to FIG. 2, the image forming apparatus 100 according to an exemplary embodiment of the present invention is an electrophotographic image forming apparatus including a case 101, and a printing unit, that is, an optical scanner 150 and a developing device 110 in the case 101.

The developing device 110 is preferably a cartridge type that is detachably mounted in the case 101. A photosensitive medium 120, a charging roller 122, a waste-toner cleaner 124, a developing roller 127, a doctor blade 128, a supplying roller 130, and an agitator 132 are installed in a developer frame 112. Additionally, a waste-toner storage 123 for storing the waste-toner that is raked from an outer circumferential surface of the photosensitive medium 120 by the waste-toner cleaner 124 and a toner storage 125 for receiving a toner, that is, a developer, are disposed in the developer frame 112. The developing device 110 is replaced with a new one when the toner stored in the toner storage 125 is exhausted.

The photosensitive medium 120 is preferably a photosensitive drum, that is, a metallic cylinder having an outer circumferential surface, on which a photoconductive material is deposited. The photosensitive drum 120 is charged to a predetermined electric potential by the charging roller 122. An electric latent image corresponding to an image to be printed is formed on the outer circumferential surface of the photosensitive drum 120 by the light scanned from the light scanner 150. The developing roller 127 develops the electric latent image into a visible image by transferring the toner onto the photosensitive drum 120 on which the electric latent image is formed. The supplying roller 130 supplies the toner to the developing roller 127, and the agitator 132 agitates the toner in the toner storage 125 so that the toner is not hardened. Additionally, the doctor blade 128 controls a thickness of the toner that is supplied from the supplying roller 130 and attached onto the outer circumferential surface of the developing roller 127. The waste-toner cleaner 124 rakes the waste-toner that is not transferred to the paper (P) and remains on the outer circumferential surface of the photosensitive drum 120. The waste-toner removed by the waste-toner cleaner 124 is stored in the waste-toner storage 123.

The transfer roller 135 faces the outer circumferential surface of the photosensitive drum 120. The visible image developed on the outer circumferential surface of the photosensitive drum 120 is transferred onto the paper (P) that passes through the transfer roller 135 and the photosensitive drum 120 by a transfer bias or the contact pressure between the photosensitive drum 120 and the transfer roller 135.

A fuser 137 includes a heat roller 138 and a pressing roller 139 facing the heat roller 138. When the paper (P) on which the visible image is transferred passes through the heat roller 138 and the pressing roller 139, the image is fused on the paper (P) by the heat and pressure.

Additionally, the image forming apparatus 100 includes a paper supplying tray 155 and a paper cassette 160 on a lower portion of the case 101. The image forming apparatus respectively includes pickup rollers 141 and 142 that pick up the paper (P) loaded in the paper supplying tray 155 and the paper cassette 160 one by one. A paper aligner 144 aligns the paper (P) before the paper (P) passes between the photosensitive drum 120 and the transfer roller 135 so that the toner image may be transferred onto a desired position of the paper (P). Additionally, the image forming apparatus 100 includes a paper discharging roller 145 for discharging the paper (P) on which a predetermined image is printed after passing through the fuser 137 to a paper discharging board 102 out of the case 101.

Operations of the image forming apparatus 100 having the above structure are described as follows. The photosensitive drum 120 is charged to a predetermined electric potential by the charging roller 122. An electric latent image corresponding to an image to be printed is formed on the outer circumferential surface of the photosensitive drum 120 in response to the light (L) irradiated from the light scanner 150. The toner in the toner storage 125 of the developing unit 110 is agitated by the agitator 162, and supplied to the photosensitive drum 120 on which the electric latent image is formed through the supplying roller 130 and the developing roller 125 to develop the image into the visible image. Additionally, the paper (P) loaded on the uppermost portion of the paper supplying tray 155 or the paper cassette 160 is picked up by the pickup roller 141 or 142, and supplied and aligned by the paper aligner 144 to pass through between the photosensitive drum 120 and the transfer roller 135. The visible image developed on the outer circumferential surface of the photosensitive drum 120 is transferred on a surface of paper (P) that faces the photosensitive drum 120. The visible image transferred on the paper (P) is fused on the paper (P) by the heat and pressure while passing through the fuser 137. The paper (P) is conveyed by the paper discharging roller 145 and loaded on the paper discharging board 102.

Hereinafter, the paper cassette 160 according to exemplary embodiments of the present invention adopted in the image forming apparatus 100 of FIG. 2 will be described.

Referring to FIGS. 3 through 5, the paper cassette 160 includes a cassette frame 161 having an inner space, an opened upper portion, and a bottom plate 162 on which the paper (P) is loaded on a lower portion thereof. Additionally, the cassette frame 161 includes a first member 170 restricting the paper (P) loaded on the bottom plate 162 from moving in a width direction thereof, and a second member 175 restricting the paper (P) from moving in a length direction. The first member 170 and the second member 175 are connected to each other by a connecting member 180 that is preferably bar shaped, and mounted on the cassette frame 161 to be linearly reciprocated.

A guide recess 164 of a straight line type is formed on the bottom plate 162. The connecting member 180 is inserted into the guide recess 164 to slide along the extending direction of the guide recess 164. Thus, the first member 170 and the second member 175 move the same distance in the same direction.

Referring to FIG. 4, the guide recess 164 is extended along a virtual straight line that is slanted from the paper supplying direction at a predetermined angle θ₁ in a clockwise direction. In the example of FIG. 4, when the first member 170, the second member 175, and the connecting member 180 that move along the guide recess 164 are fixed, two kinds of paper (P1 and P2) that have different sizes may be loaded. If the angle θ₁ is set as 18.4°, the paper of A4 size that is generally used (P1) and the paper of letter size (P2) may be loaded on the bottom plate 162. The paper of letter size (P2) has a shorter length and a larger width than those of the paper of A4 size (P1).

The paper cassette 160 further includes a position fixation unit for fixing the positions of the first member 170, the second member 175, and the connecting member 180. A boss 176 that protrudes downwardly (refer to FIG. 5) is formed on a lower end portion of the second member 175. A first groove 166 and a second groove 168 that are adapted to receive the boss 176 are disposed on the bottom plate 162. Referring to FIG. 5, when the boss 176 is received in the first groove 166, the paper of A4 size (P1) may be loaded on the bottom plate 162. When the boss 176 is received in the second groove 168, the paper of letter size (P2) may be loaded on the bottom plate 162.

A slant surface 177 is formed on an upper end portion of the second member 175 so that the end portion of the paper may be guided to an appropriate position on the bottom plate 162. A stepped surface 178 is formed so that the loaded paper cannot escape from that position. The first member 170 also includes the slant portion and the stepped portion as in the second member 175.

If a user wants to print the image on the paper of A4 size (P1), the connecting member 180 is moved along the guide recess 164 until the boss 176 is received and fixed in the first groove 166 and the paper of A4 size (P1) is loaded on the bottom plate 162. If the user wants to print the image on the paper of letter size (P2), the connecting member 180 is moved along the guide recess 164 until the boss 176 is received and fixed in the second groove 168 and the paper of letter size (P2) is loaded on the bottom plate 162.

FIG. 6 is a top plan view of a paper cassette according to another exemplary embodiment of the present invention.

Referring to FIG. 6, the paper cassette 260 also includes a cassette frame 261 having a bottom plate 262 on which a guide recess 264 is formed. A first member 270, a second member 275, and a connecting member 280, of substantially bar shape, connects the first and second members 270 and 275 and is inserted into the guide recess 264. The guide recess 264 is extended along a virtual straight line that is slanted in the clockwise direction at a predetermined angle θ₁ with respect to the paper supplying direction. The angle θ₁ is preferably about 18.4°, and the paper of A4 size (P1) and the paper of letter size (P2) may be loaded on the paper cassette 260.

The connecting member 280 includes an elongated recess 281 that is extended in the extending direction of the guide recess 264 and a rack portion 282 having gear teeth is formed on an inner side surface of the elongated recess 281. Additionally, a pinion gear 285 that engages the rack portion 282 is rotatably installed on the bottom plate 262. Accordingly, when the pinion gear 285 is rotated in the clockwise or counter-clockwise direction, the connecting member 280 and the first and second members 270 and 275 connected to the connecting member 280 are linearly moved in the extending direction of the guide recess 264.

A lever 287 for rotating the pinion gear 285 at a predetermined angle is extended under the bottom plate 262 from the pinion gear 285 to a side, and an end portion 287 a of the lever 287 protrudes over the bottom plate 262. The bottom plate 262 includes a lever guide recess 290 having a substantially arcuate shape that guides the proceeding direction of the lever end portion 287 a. When the lever end portion 287 a is located at an end 290 a of the lever guide recess 290, the paper of A4 size (P1) may be loaded on the bottom plate 262. When the lever end portion 287 a is located at the other end 290 b of the lever guide recess 290, the paper of letter size (P2) may be loaded on the bottom plate 262. Since the lever end portion 287 a may be moved between the end portion 290 a and the other end portion 290 b of the lever guide recess 290, the one end portion 290 a and the other end portion 290 b of the guide recess 290 perform the function of a stopper to prevent further movement of the connecting member 280.

The paper cassette 260 further includes a size recognition unit that recognizes whether the first member 270 and the second member 275 are set to be suitable for the A4 size paper (P1) or for the letter size paper (P2) to determine the size of paper that may be loaded on the bottom plate 262. A first switch 292 may be formed on the end 290 a of the lever guide recess 290, and a second switch 294 may be formed on the other end 290 b of the lever guide recess 290.

When the lever end portion 287 a is located at the end portion 290 a of the lever guide recess 290, the lever end portion 287 a contacts the first switch 292 to generate a sensing signal, and the sensing signal is transmitted to a controller (not shown) of the image forming apparatus. Therefore, a message representing that the paper cassette 260 is set to be suitable for the A4 size paper may be displayed through a display panel (not shown) formed on the case 101 of the image forming apparatus 100. Additionally, when the lever end portion 287 a is located at the other end portion 290 b of the lever guide recess 290, the lever end portion 287 a contacts the second switch 292 to generate a sensing signal, and the sensing signal is transmitted to the controller of the image forming apparatus 100. Therefore, a message representing that the paper cassette 260 is set to be suitable for the letter size paper may be displayed through the display panel formed on the case 101 of the image forming apparatus 100.

FIG. 7 is a top plan view of a paper cassette according to a third exemplary embodiment of the present invention.

Referring to FIG. 7, the paper cassette 360 includes a cassette frame 361 having a bottom plate 362 on which a guide recess 364 is formed and a first member 370, a second member 375, and a connecting member 380 connecting the first and second members 370 and 375. Additionally, the paper cassette further includes a position fixation unit for fixing the set position of the first and second members 370 and 375. The position fixation unit may be the same as that of the above exemplary embodiments.

However, the guide recess 364 is extended along a virtual straight line that is slanted in a counter-clockwise direction at a predetermined angle θ₂ (0°<θ₂<90°) with respect to the paper supplying direction. Additionally, the connecting member 380 includes a connecting portion 381 that connects the first and second members 370 and 375. A guide portion 382 is inserted into the guide recess 364 to be linearly moved along the guide recess 364.

Therefore, the bottom plate 362 of the paper cassette 360 may load a kind of paper having a predetermined size (P3), and another kind of paper having larger width and length than those of P3 (P4).

According to the present invention, there is no need to set independently the first member and the second member when the paper cassette is set according to the size of the loaded paper. Thus, the setting operation of the paper cassette may be performed in a convenient and easy manner. Additionally, the possibility of generating a jam due to being used by an unskilled user is reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. 

1. A paper cassette, comprising: a cassette frame having a bottom plate on which sheets of paper are loaded; a first member restricting the paper loaded on the bottom plate from moving in a width direction of the paper; a second member restricting the paper from moving in a length direction; and a connecting member connecting the first member and the second member and mounted on the bottom plate to be linearly reciprocated.
 2. The paper cassette of claim 1, wherein, a guide recess extends substantially linearly in the bottom plate, and the connecting member is mounted on the bottom plate to be linearly reciprocated along the guide recess.
 3. The paper cassette of claim 2, wherein the guide recess is extended along a virtual line that is slanted in a clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.
 4. The paper cassette of claim 2, wherein the guide recess is extended along a virtual line that is slanted in a counter-clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.
 5. The paper cassette of claim 1, wherein the connecting member includes a rack portion where a gear is formed, and the bottom plate includes a pinion gear that engages the rack portion such that the connecting member is linearly moved by the rotation of the pinion gear.
 6. The paper cassette of claim 1, wherein a position fixation unit fixing positions of the first member, the second member, and the connecting member according to the size of paper.
 7. The paper cassette of claim 1, wherein a size recognition unit recognizes the size of the paper that is loaded on the bottom plate in a position where the first and second members are set.
 8. The paper cassette of claim 1, wherein a slant surface is formed on upper end portions of the first and second members to guide the paper to an appropriate loading position when the paper is loaded.
 9. The paper cassette of claim 8, wherein a stepped surface is formed on upper end portions of the first and second members to restrict the loaded paper from escaping that position.
 10. The paper cassette of claim 1, wherein said first member is substantially perpendicular to said second member.
 11. An image forming apparatus, comprising: a printing unit printing images; and a paper cassette loading sheets of paper that are supplied to the printing unit,the paper cassette including a cassette frame having a bottom plate on which sheets of paper are loaded; a first member restricting the paper loaded on the bottom plate from moving in a width direction of the paper; a second member restricting the paper from moving in a length direction; and a connecting member connecting the first member and the second member and mounted on the bottom plate to be linearly reciprocated.
 12. The apparatus of claim 11, wherein a guide recess extends substantially linearly the bottom plate, and the connecting member is mounted on the bottom plate to be linearly reciprocated along the guide recess.
 13. The apparatus of claim 12, wherein the guide recess is extended along a virtual line that is slanted in a clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.
 14. The apparatus of claim 12, wherein the guide recess is extended along a virtual line that is slanted in a counter-clockwise direction at a predetermined angle that is larger than 0° and smaller than 90° with respect to a supplying direction of the paper.
 15. The apparatus of claim 11, wherein the connecting member includes a rack portion where a gear is formed, and the bottom plate includes a pinion gear that engages the rack portion to linearly move the connecting member by the rotation of the pinion gear.
 16. The apparatus of claim 11, wherein a position fixation unit fixes positions of the first member, the second member, and the connecting member according to the size of paper.
 17. The apparatus of claim 11, wherein a size recognition unit recognizes the size of the paper that is loaded on the bottom plate in a state where the first and second members are set.
 18. The apparatus of claim 11, wherein a slant surface is formed on upper end portions of the first and second members to guide the paper to an appropriate loading position when the paper is loaded.
 19. The paper cassette of claim 18, wherein a stepped surface is formed on upper end portions of the first and second members to restrict the loaded paper from escaping that position.
 20. The paper cassette of claim 11, wherein said first member is substantially perpendicular to said second member. 